Had an idea for a new item, something I don't think has been seen before :D.
An armor piece that's unique passive is when you generate 50 points of health, you gain .02 AD (Not permanent). Not affected by summoner spells or Lifesteal, or excess healing from Runes. Being healed by another champion resets the effect. No max cap on hp regenerated by a max cap of maybe 50 - 75 extra AD (High, but considering how much HP you'd need to SOLELY regen, I think it's balanced).
Paired with Garen or Volibear early, this would probably be really strong though lol.
Maybe stats would be something like +400 hp, +20 Armor.